*{
    margin: 0;
    padding: 0;
}
body{
    background-image: url(./img/bg2.jpg);
    background-size: 100%;
}
#gameCanvas{
    /* 共同决定使其居中 */
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
    margin: auto;
    /* width: 200px;
    height: 400px; */
    /* background-color: tan; */
}
#nextCanvas{
    position: absolute;
    top: 20px;
    left: 20px;
    /* width: 100px;
    height: 50px; */
    background-color: tan;
}
#score{
    position: absolute;
    top: 20px;
    left: 0;
    width: 100%;
    height: 50px;
    text-align: center;
    line-height: 50px;
    color: white;
}
img{
    position: absolute;
    width: 50px;
    height: 50px;
}
img:nth-child(4){
    top: 20px;
    right: 20px;
}
img:nth-child(5){
    left: 20px;
    bottom: 150px;
}
img:nth-child(6){
    right: 20px;
    bottom: 150px;
}
img:nth-child(7){
    left: 20px;
    bottom: 50px;
}
img:nth-child(8){
    right: 20px;
    bottom: 50px;
}